Commutator-turning lathe



H. G. MILLER COMMUTATOH TURNING LATHE 3 Sheets-Sheet l Filed Oct. 20, 1926 ATTORN EY Dec., 30, i930. H. G. MILLER COMMUTATR TURNING LATHE Filed Oct. 20, 1926 3 Sheets-SheetI 2 Dec. 30, 1930. H. G. MILLER COMMUTATOR TURNING LATHE 3 Sheets-Shea?l 3 Filed Oct. 20, 1926 lNvENroR l v y /mw BY WWA i A] ATTORNEY atented Dec. 30, 1930 Till COMMUATOR-TUB-NNG LATVIE Application led ctober 2i), 1926. Serial No. 142,841.

T his invention relates to improvements in commutator turning lathes designed particu larly for turning commutatore of small generators and motors such as are employed in motor driven vehicles `utilizing starting and lighting circuits, also to an improved method tor turning commutators. Y

Vlie primary object of this invention Vis to provide special lathe peculiarly adapted for garage service and which will be adapted tor use in turning the commutators of all types of generators and starting motors used in motor driven vehicles, handily, quickly and with such good j ob results that the surfaces ofthe commutatore will become absolutely concentric to the axis upon which the rotor turns when in use.

Ancillary objects are to provide means iifhereby the rotors of generators and motors, with their bearings, may be removed from their mountings in motor driven vehicles and the bearings of each utilized in the turning machine to support the rotor while the commutator is being turned ;-to provide convenient and etlicient means associated with the turning machine for actuating the rotorduring the cutting or turning operation upon its commutatorg-to provide a special turning machine ot the described type, which can be readily adjusted and re-adjusted in accordance with the requirements ot any particular commutator turning ob by any garage mechanic oi ordinary slrillg-to provide a commutator truing and grooving mechanism which can be used throughout extended periods ot time by various mechanics exercising merely ordinary care, without material deterioration of the mechanism ,-to provide tools and mountings therefor, of such character that the tools can be readily removed(` sharpened and re-placed in their mountings without danger ot mal-adjustment and in which such tools will operate upon the work with maximum efficiency to provide a suitablecutting tool for turning the commutator, in association with a groove ing cutter and means for operating the same for grooving thD Vinsulation between the conimutator hars after a turning operation gand in general to provide a self-contained specialV turning unit in which thework can be quickly and accurately centered, the turning and grooving operations speedily performed with extreme accuracy and from which the worlr can be quickly removed and replaced in a `motor driven vehicle (or in position for other use) with minimum loss of time. i

In the drawings Figure l is a front elevation, partly in vertical section, oit a turning rmachine em bodying my invention asvit appears with a generator o1c one type centered and connected with suitable driving mechanism preparatory to a turning operation.

Figure 2 is a plan view of the same.

Figure 3 is a. detail Yface'view of a mounting tor theV cutter disk or blade.

Figuret is a c etail face view of the turning cutter, with an associated grooving cutter.

Figure 5 is a detail sectional view of the cutter mounting and cutter, drawn on line 5 5 of Figure t.

Figure 6 is a sectional view (enlarged) drawn on line 6 6 oli Figure 5 and showing the mounting for the grooving cutter.

Figures 7 and 8 are sectional views drawn, respectively, on lines 7--7 and 8 8 of Figure 2.

Figure 9 is a detail sectional view of one ot the interchangeable head stock mountings for supporting a generator bearing.

Figure l() is a detail view of a chip guard for the same.

Figure 1l is a detail view of' the center rest in direct engagement with the outer bearing member or raceway of a motor.

Figure l2 is a detail view of a modified means for driving the rotor while its commutator is being turned.

Figure 13 is a detail showing modified centering means.

Lilre parts are identied by the same reference characters throughout the several views.

The base 20 is chambered and provides a housing for an electric motor 21, which may besecured within the base in any suitable manner as indicated by the hangers Q2. The

head stock 23 and tail stock 24 are adjustably mounted for longitudinal movement along the bed plate 25 which is longitudinally grooved as indicated at 2G in Figure 2, whereby the head and tail stocks may be slidingly interlocked with the base and secured by their respective clamping bolts 27. The head stock spindle or work holder comprises a longitudinally n'iovable bar or shaft 30 which may be axially moved by a feed rew 3l of ordinary type in threaded engagementwith said bar. The spindle bar or shaft 30 is suitably socketed to receive the tapered shank 32 of any one of a series of cup-shaped work holders 33 of differing sizes. Each work holder 33 is provided with a set of bushings 34;, each of which has an internal diameter which corresponds with the external diameter of the outer bearing ring or raceway of at least one generator or motor of known type. The bearing ring or raceway here referred to is the one associated with the motor shaft adjacent to the commutator, and is the right hand bearing as viewed in Figure l. The terms right and left as used throughout this specification, have reference to the position in which the machine is illust-rated in Figure l.

The tail stock spindle comprises a tubular member 37 having a threaded plug 38 at one end and an annular flange 89 at the opposite end. Member 37 forms a socket to receive a centering pin 410 having a tapered point 41 to engage the work, i. e. the end of the mot-or or generator shaftto be supported by the tail stock. The centering pin is provided with a socketed sprin g seating which receives a coiled spring 43, one end of which bears aga-inst the plug or nut 3S. A bolt 44, extending through an aperture in the nut 38, holds the centering pin with the spring partially compressed and therefore the centering pin is resiliently supported for Contact with the work.

The tubular spring receiving` portion of the pin may, however, be forced into contact with the nut 3S in which case further yielding movement is not possible. For some classes of work this is desirable. By properly adjusting the tail stock with reference to the head stock.v the head stock spindle may be fed inwardly by its feed screw 3l to push the centering pin against the nut 8S when the work is to he supported positively against yielding longitudinal movement.

The centering pin il carried by the tail stock is primarily used for supporting the work pending adjustment of an auxiliary positioning device which mai7 be termed a. cut-ter rest for the purposes of this description in View of its similarity to the center rests used in ordinary lathes, although it is used in my improved lathe for more precise centering than can be obtained by the centering pin 40. This center rest is adjnstably mounted upon the bed pl ate 25 and comprises @essere a base portion l5 provided with a clamping bolt 27 similar to the clamping bolt 27 which connect the head and tail stocks to the base. The base portion l5 of this center rest carries an annular mounting fra-me rormed in two sections 46 and L.t7 which are hinged together at 48 whereby the upper section 47 may be swung` backwardly as indicated by dotted lines in Figure 8 when the work is being initiz lly centered. The member #i7 may then be adjusted in closed position as indicated by full lines in Figure 8 and locked in this position by a bolt 4:9 which is pivoted to thelower section -lh and adapted to be swung upwardly between the fork arms 50 on the swinging end of section 47, whereupon the clamping thumb nut l carried by the bolt may be turned down to a position for clamping pressure upon said fork arm.

By adjusting this center rest longitudinally of the bed plate it may be so positioned that the ring sections 46 and lt7 will encircle the left h and bearing of the generator or motor shaft, whereupon said bearings may be engaged and properly centered by a set of radialhv extending chuck screws 55. preferably three in number, and adapte-d to furnisli a three point support for the outer bearin collar or raceway in which the motor shaft is mounted. In some instances the bearing is encased and in that event the chuck screws engage and support the casing as shown Figures 1 and 8 where4 they are illustrated as engaging the hub 58 of a motor casing end plate 59. The three chuck screws are 1200 apart and it is therefore obvious that they can be adjusted in such a manner as to co-operate with the head stock or work holder chuck 33, in so centering the work that the motor may run true in its own bearings.

It will, of course, be understood that the resiliently mounting centering pin may be forced to yield to some extent if the socket in the motor shaft in which this pin engages should be slight-ly out of center. By thus yielding it will accommodate itself to the center established by the adjustment of the chuck screws e rlhe work may thereupon be rotated by the lathe motor 2l which has a shaft 60 provided with a driving pulley 6l, operatively connected in any suitable manner to actuate the work. In Figure l. the pulley Gl'transmits power through a belt 62 which may be adjusted to encircle the wor i. e. the armature 63 of the motor to be machined. The belt 62 runs over idle pulleys 64- and 65 at the rear of the machine.

The tool holder and feed mechanism will now he described. The tool holder comprises an arm or lever 70. which secured to the tool feed bar 7l and its swinging end portion is provided with an operating handle "2. Near the handle. an adjustable stop, such l as the screw 7 3 is employed to support the arm from a rest 74, which is adjustably VLenaerts lmounted in the head stock and normally locked thereto by setscrew The arm or tool holder vis provided with an oblique seating face 77 receive the cutter 7S. The cutter illustrated comprises a generally dislr shaped blade pro-vided with a which are contoured Yto forni a cutting point or edge at 81 (Figure el) which is adapted to be fed into contact with the peripheral surface ot' the commutator to be machined hereinafter explained. The connnutator is shown at 83 in Figures 1 and 2. Tae cutter blade is preferably supported by the seating face of the holder arm 70 in a vertical plane which is oblique tothe axis about which the work rotated, the point or cutting edge S1 of the blade being positioned substantially in a helical cutting line generated by rotation of the worl; and simultaneous progressive feeding of the blade along the surface to be .machined at a normal rate of feed. The cutter blade is provided with a supporting stem 35 which has a counter-sunk head and clamping nut 86. rlhe bolt passes through an aperture in the holder and .is splined thereto. 1When the clamping pressure is relieved the blade may be rotated upon stein 85 to'position the cutting edge or point 81, or to bring into cutting `position an auxiliary or groove cutter as hereinafter explained.

The tool holder arm 70 preferably has its seating tace 77 provided with a plurality of apertures 79, (Figure 3), each adapted to receive a blade stein 35 whereby bladesniay be adjusted to the seating face at different distances Jfrom the axis about which the worlr rotates in accordance with the requirements 'for commutatore of dii'lering diameters. lntermediate adjustments are obtained by the stop screw 7 3 in cooperation with the rest '74.

The tool holder arm '70 is urged in the direction of the rest 74 by a compression spring 92 which is coiled about a rod 93 with its lower end bearing upon the bed plate and its upper end bearing against the short arm 9% oi' said lever. The rod 93 is pivoted to said short arm and extends through an aperture in the bed plate 25. rlhe arrangement is such that when it is desired to remove the tool from the work, the handle 72 may be lifted and swung backwardly until the short arm swings plast line of centers between the anis of the tool ieed bar. 71 and the of the rod 93 in the apertured bed plate 25. Thereupon the recoil or reactionary pressure oi' the spring 92 will tend to hold the arm '70 peripheral notch 30, the marginal walls of and thetool in its retracted position. stop projection 95 on the short arm 94 strikes rod 93 limits the backward movement of the arm 70 when in this position.

rlhe tool Jeed bar 71 may be actuated for a slow machine feed by a feed screw 96 operating through a feed nut 97. This feed nut 9.7 is screwed into the outer end of a sliding or tubular spindle 98 in which the feed bar is mounted and interloclred by a feed bar lange 99 engaged between a shoulder 100 on the spindle 93 and the feed nut 97. The leed screw 96 has a shank 102, swiveled within a sleeve 103 and against the inner end oit which the annular feed screw flange 10ft abuts. The inner end portion of the sleeve tion is accomplished by the manually operable crank 108. But thissleeve will be released by retracting the set screw 108 when rapid traverse movements are desired. Y

ln order to provide for rapid traverse movements of the feed bar 71 the spindle 98 is provided with a rack 110 along its rear side. A pinion 111, mounted upon a ver ical. shaft 112, has its teeth in mesh with this rack. This vertical shaft 112 is supported in head stoclr bearingsk and may be manually actuated by the crank 113. `When the spindle is to be thus actuated by ineansoi the pinion and raclr sleeve 103 will be released from cap 105 by retracting ,the set screw 107 and thereupon the sleeve, feed screw, eednut, spindle andieed bar 71 may all be moved axially as a unit by rotating the pinion 111.

"The rapid traverse movement will be utilized principally for actuating groove cutter 90 and this will now be described. rlhe groove cutter 90 comprises a thin blade adapted to be utilized for grooving the insulation (mica) between the commutator bars after the commutator has been machined, thereby prevent` ing the insulation from projecting beyond the periphery of the reduced commutator or from extending into a position where parti"- cles abraided from the commutator bars may accumulate on the mica or other insulation sufliciently to short circuit the bars. rlherefore the blade 90 is of a thickness correspond ingto the ordinary gap between the commutator bars, and it is mounted against an oblique seating face on the main cutter blade 78 which compensates for the pitch of the tool holder seating face 77 in such a manner that the blade 90 will occupy a plane parallel to the aXi-s of the tool feed bar 71, whereby when the crank or actuating lever 113 is swung to the left, motion will be transmitted through the pinion 111 and will actuate the tool feed bar 71, tool holder 70 and the tool 90 longitudinally of a registering groove in thc commutator 83, if the main cutting blade 7 8 has been properly adjusted to bring the grooving tool 90 into a vertical position of downward projection from the axis of the tool blade stem 85. Grooving tool 90 is triangular (equilateral) in cross section. To facilitate quick adjustments of the main cutter blade 78 whereby either the cutter 81 or the cutter 99 may be brought into cutting position, the tool holder 70 is preferably provided with a resilient feeler adapted to enter registering sockets in the inner face of the blade 78, as best shown in Figure 5. This feeler comprises a plunger 11T seated in a transverse bore or aperture in the tool holder 70 with a spring 118 interposed between the plunger and the threaded plug 119. A ball 120 is interposed between he end of the plunger' and the inner face of the blade T8, and the sockets 121 in the blade partially receive this ball when in registry with it, the ball serving as a partial lock to hold the blade in position and interposing sufficient resistance to rotative movemei'it of the blade to advise the user of the fact that the ball is in position in the registering socket,

one socket will register with the ball when the cutter 81 is in cutting position and the other will register with the ball when the cutter 99 is in cutting position.

rPhe oblique seating face 115 is preferably formed by notching the blade 78, as best shown in Figure G, and the blade is secured against said seating face by a wedge block 122, and a suitable fastening such as screw 123. It has been stated that any suitable means for rotating the armature during a cutting operation may be employed. A convenient means for this purpose is illustrated in Figure 12 and this means will ordinarily be j n'eferredtothe belt drive illustrated in Figures 1 and 2 for the reason that it can be quickly adjusted into and out of operating position to facilitate positioning armatures in the lathe and the adjusting means can be actuated from the front of the machine. rlfhe mechanism illustrated in Figure 12 is also adapted to exert downward pressure upon the ar1nature and its shaft bearings thereby more nearl approximating the conditions over which tlie armature rotates when in use.

In Figure 12 the lathe motor pulley 61 is connected by a belt 125 with a pulley 126 mounted in fixed bearings above the rear portion of the bed of the machine. This pulley 126 is directly connected with a roller 127 over which a wide armature actuating belt 128 passes. This belt being also passed about a co-operat-ing roller 129 supported in .front of the armature by a vertically sliding frame 130 in which the roller trunnions 131 are journaled. The frame 180 may be locked in a desired position of elevation by set screws 132 whereby the roller 129 may be lifted and carry the belt 12S out of contact with the armature, or lowered to the position indicated by full lines in Figure 12 in which position it may be utilized to rotate the armature during a machining operation.

Briefly reviewing the operation of the ma` chine it will be understood that the armature to be machined will be removed with its bearings from its mountings in the motor driven vehicle or other place of use, and initially centered in the lathe by engaging the bearings at the commutator end of the machine in a suitable holder or chuck 33, (Figure 9), a bushing 34 being employed when required in order to obtain a close fit. The other end of the commutator shaft will be rough centered by engagement with the point l1 of the centering pin l0. Thereupon the feed screw 31 may be turned to feed the head stock spindle toward the tail stock until suiiicient pressure is exerted upon the work to hold it in position. The center rest screws will then be actuated until their inner ends engage the left hand bearing of the motor or generator shaft (or the hub of its associated holder 59), and the several screws will be relatively adjusted until the armature is found to revolve concentric to the axes of the spindles. The driving belt having been applied to the armature and the cutter 81 being in cutting po sition the lathe motor will then be started and the cutter progressively fed alongv the commutator surface by the slow or tool reeding movement derived by rotation of the feed screw 96 with the swiveled sleeve 103 locked to the head stock by the set screw 107. Owing to the fact that the bearings for the motor or generator shaft, which is being machined, will necessarily be exposed to the chips cut from the con'imutator it will be found advisable to cover the chuck 33 with a suitable chip guard 135 such as is shown in Figure 10.

After the surfaces of the commutator bars have been machined by the cutter 81, the cutter disk '.78 will be released for rotative adjustment by slightly retracting the clanip ing nut 86. Thereupon the blade or disk 78 will be rotatively adjusted upon its stem 85 until the ball 120 seats in the socket 121 which indicates a proper positioning' of the grooving tool 90. The blade will then be again clamped into position by the nut 86, the feed screw 96 locked to the head stock by the set screw 107 and the tool holder and tool reciprocated by means of the crank or lever 113. Pending this operation the lathe motor will be stopped and the work will be rotated by hand to bring` the insulation between the respective commutator bars successively into position for registry with the blade 90, the latter being reciprocated to groove out the space between each pair of bars and the work being then rotated manually to a distance equal to the width of a commutator bar preparatory to the next grooving operation.

It will be understood that the special lathe herein described may be used for supporting armatures which are not provided with anti-friction bearings, if such armau head stock spindle chuck and with the cen-L I tering nin of the tail stock. lt will be undesirable to use the center rest screws in that event unless' means for a suitable bearing ring is provided for the shaft andsdirectly engaged by the ends of the screws.

l preferito use a belt in preference to a friction rollerfor actuating the armature for the reason that ordinary armatures for conductor bars which have outer or peripheral surfaces spaced in suoli a manner that va friction wheel contacting along a line Vparallel to vthe axis of the armature would tend toenter the spaces between the bars and a vibration would thus be set up in the armature which would interfere with the accurate machiningthereof. The Yuse of the belt also facilitates obtaining an extended area of frictional driving contact with the periphery of the armature, whereby the armature may be revolved under light pressure exerted by the belt thereon.

The use of a center rest chuclr or equivalent means for supporting the left hand bearings of the armature and holding such bearings securely in' position, enables me to utilize the feed yscrew o-f the head stock work spindle for applying pressure to the chuclred right hand bearing ring in such a manner that the bearing cones will be axially shifted to take up any slack resulting from wear and this aids in accurately centering the armature.

In Figure 13, I have shown special means for centering an armature for which no antifriction bearings have been provided. The

head stock chuck cup is provided with a shaft engaging bushing 140. The center rest is removed and the centering pin taken out of the tail stock. rEhe latter will then receive a bushing 141 which lits the portion of the armature shaft adjacent'to the armature and allows the tail stock to be moved into proximity thereto.

l claim:

l. ln a commutator turning lathe, the combination of means for supporting and centering an armature in its own bearings, a tool holder, a tool feed bar, a hollow spindle mounting for said bar, a feed screw for slowly actuating the bar together with the spindle, rack and pinion mechanism for reciprocating the spindle and feed screw along a line parallel to the 'axis of the armature, means forlocking the feed screw 'against reciprocation, and turning and grooving tools for the tool holder.

2. In commutator turning lathe, the combination with a head stock, of a tool holder spindle provided with a rack, a manually operable pinion in mesh with the rack, a tool' feed bar vmounted inthe spindle, a feed screw forV actuating the feed bar and spindle, bearings therefor, means for locking and releasing said bearings, and a tool holder provided with turning and grooving tools interchangeably adjustable to position for operation upon the work.

V3. ln a commutator turning lathe, a head stock centering chuck adapted to receive the outer ring of 'an armature shaft bearing for supporting one end of such shaft, a tail stock provided with a yieldable centering pin adapted to engage the other end of said shaft, and intermediate centering devices adapted to engage and support armature shaft bearings adjacent to the tail stoel; and adjustable for centering purposes independently of the tail stock centering pin, means for rotating the armature upon its own bearings while so centered, Vand means for feeding a machine tool along the face of the commutator during such rotation.

Ll. A commutator turning lathe including the `combination with head and tail stock members, of means for centering and supporting anarmature therefrom for rotation upon its own bearings, friction driving mechanism for rotating thearmature while so supported, and means, associated with the head stock, for machining the armature commutator during such rotation, together with `a grooving tool supported by the machining means and rap-id traverse mechanism for reciprocating such tool.

5. A commutator turning lathe, including the combination with a hollow base provided with a lathe motor, Arelatively adjustable head and vtail stock membersmounted on the base, an intermediate centering member adapted to receive and support armature. bearings, a head stock centering member also adapted to receive and support armature bearings, a tail stock centering device adapted to engage and support an armature shaft while its bearings are being centered, means for utilizing the lathe motor for actuating a belt in driving relation to the armature and manually operable means for simultaneously feeding a machine tool alongthe surface of its commutator.

6. In a commutator turning lathe, the combination with head and tail stock members, of means for centering and rotating an armature in its own bearings between the head and tail stock members, a head stock tool supporting spindle provided with a rack, a manually operable pinion in mesh with the rack, a tool holder bar supported by and movable axially along said spindle, a feed screw for actuating the bar, and a feed nut supported from the spindle to means for locking the feed nut and spindle to the head stock.

7. In a commutator turning lathe, the combination with a head stock, of a tool holder, a tool holder bar, a reciprocable mounting for the Y bar means for locking the mounting against reciprocation, and manually controlled means for selectively reciprocating the mounting in rapid traverse or actuating the bar Within the mounting in slow feed. j

S. 'In a commutator turning lathe, the combination with a head stock, of a tool holder, a tool holderbar, a rcciproceble mounting for the bar, and manually controlled means 10 for selectively reciprocating the mounting in rapid an d slow feeds, said bar being provided with a tool holder and a rotatable member thereon adapted to support a turning tool in f )lane oblique to the har and a grooving tool 'il-ane parallel to the bar. 0. In a` commutator turning lathe, the comunali-:in with a tool holder, of a machining ool supported thereby and rotatably adjustible aboutI1 e. axis of its support, and a fricoviug too.. mounted upon said inachini'ng tool and adapted to be moved to grooving posi ion when the machine tool is adjusted to a predetermined inoperative position. i

10. In a commutator turning lathe, the 3L-combination with a' tool holder of a ma- :chining tool supported thereby and rotatably adjustable about the axis of its support, and a grooving tool mounted upon said machining tool and adapted to be moved to grooving 3o position when the machine tool is adjusted to a predetermined inoperative position, together with a feed screiv for actuating the tool holder at a machining speed, and auxilialry rapid traverse mechanism for reciproeating the tool holder and grooving tool.YV

11. In a commutator turning lathe, the combinationof means for supporting and centering armatures of differing sizes for rotation upon their ovvn bearings, a lathe motor, and an armature driving belt adapted to be adjusted int-o and out of frictional driving relation to the armature, and operatively con- 'ncctedvith the lathe motor.

12. In a cominutator turning lathe, the combination ofY meansV for supportino and centering armatures of differing sizes Ior rotation upon their oivn bearings', and a lathe niotor. an armature driving belt adapted to be adjusted into and out of frictional driving relation to the armature, and operatively connected with the lathe motor, said lathe being provided with an oblique faced machine tool mounting, a feed screw for actuating said mounting along thearmature axis and a disk es shaped Icutter blade rotatively adjustable upon said mounting and provided With a machining cutter and a grooving cutter, each adapted to be separately brought into operative position by rotative adjustmentn of said co blade. i Y

13. In a commutator turning lathe, the combination of means for supporting and centering armatures of differing sizes for rotation upon their own bearings, and a lathe l inc-tor, a armature driving belt adapted to be adjusted into and out of frictional driving relation to the armature, and operatively con nected with the lathe motor, said lathe being provided. with an oblique faced inachinewtool mounting, Va feed screw for actuating said mounting along the armature axis and a disk shaped cutter blade rotatively adjustable Y,joonsaid mounting and provided with a machining cutter and'a. grooving cutter, each adapted to be separately brought into operative position by rotative adjustmentof said blade, said blade being adapted to be secured to the tool holder at different distances from the armature axis, whereby to position the tools for use upon commutators of differing diameters. Y

14. In a commutator turning lathe, the combination with a tool feed spindle, of a tool holder supported therefrom, a feed screw for actuating the tool holder, a tool blade positioned Von the tool holder in a planeV ob liqne the axis of :the spindle and provided with a cutting tool,*a grooving tool mounted on the tool blade in a plane parallel to the axis of the spindle and means for actuating the tool holder along a line parallel to said axis at different speeds.

15. In a commutator turning lathe, the combination with a Work supportingrspindle and a tool supporting feed bar, Yan arm adapted to oscillate about the axis of the feed bar and provided with a seating face oblique to said axis, said arm havin(JV a plurality of apertures extending through said seating face, an adjustable tool positioning stop carried by said arm, rest adapted to be engaged by said stop, and a tool carrying blade having a stein adapted to be interchangeably engaged in said apertures and additionally positioned by said stopat various distances from the axis of the Work supporting spindle.

16.Y In a cominutator turning lathe, the combination with a Work supporting spindle and a tool supportingfeed bar, an arm adapted to oscillateV about t-he axis of the feed bar and provided with a seatingrface oblique to said axis, said arm having a plurality of apertures extending through said seating face, an adjustable tool positioning stop carried by said arm, a rest adapted to be engaged by said stop, anda tool carryingblade having a stem adapted to be interchangeably en` gaged in said apertures and additionally positioned by said stop at various distances from the axis of the Work supporting spindle, said tool carrying blade being provided with a seating face for a grooving tool in a plane compensating for the oblique pitch of the tool holder seating face, and said blade being rotatively adjustable upon its stem to move the grooving tool into and out of position for use. Y

17. In a commutator turning lathe, a Work holding head stock spindle provided with a feed screw and a work engaging chuck of a tail stock provided With an axially yielding centering pin in alignment with the il of the head stool; spindle, a spring to urge the centering pin in direction oi head stoch spindle, means for limiting the the pin in that direction, and a movement or stop adapted to limit trie movement of the pin in the o posite direction, together With associated means for supporting an armature shaft upon its own bearings With ts afgis in alignment with the head stock spindle and With centering pin.

i8. ln a conimutator turning lathe, the combination with means 25er supporting the armature for rotation in its own hearings, a tool feed bar having an axis parallel with the axis of armature rotation, a tool holder secured to said bar and having one arin provided With a seating face oblique to said axis, a tool support adjustable upon said seating i'ace, means tor resiliently urging the tool holderl in one direction and an adjustable stop for limiting the tool holder in that di rection.

19. ln a coinmutator turning lathe, a tool supporting bar provided With a feed screw, a tool holder carried by said loar and having one arm provided with a tool receiving' face and another arni proviced With a swinging linlt rod, a guide for the lower end of said link rod, a compression spring interposed he tween the guide and tile arm to which the link rod is connected, whereby the tool holder is urged in one direction about the anis of its supporting bar, a relatively fixed rest, an adjustable stop carried by the tool holder and adapted to engage the rest'to limit the movement or' the tool holder in one direction, a machining tool carried hy the tool holder, and means for supporting an armature in its own hearings for rotation about an aXis parallel to that of the tool holder bar with its coinmutator in position to he machined hy said tool.

20. The method of machining armature connnutators consisting in centering the armature in a lathe upon an axis corresponding` with that ot its normal rotation, applyingV frictional driving pressure to the periphery of said armature to rotate the same, and simultaneously feeding a cutting tool along a line parallel to said axis in cutting relation to the coinmutator.

2l. lin a coniniutator turning lathe the combination with a head stoclr, of a tool holder, a supporting tool holder har, a reciprocahle mounting for the har, a feed screw adapted to actuate said har and provided with siviveled head, a supporting sleeve 'for the swiveled head adapted to travel With the mounting, and means for locking said srriveled head against movement When the feed screw is being operated, whereby th may equipped with a groovi'- j machining cutter and actuatc armature coiinnatator during such rotation.

Means nachining an armature com` mutator mounted on shaft supported in a hearing at one end, comprising a cen ring device for the bearing, a head and `l i o ciated With tue head stock iior machining the tai engaging the opposite ends of thc shaiC justahie heltinej adapted to he moved and out oi d lying relation to the armature so supported, motor driven means for actuating the Toelti and manually controlled tool feeding means for actuating tools along t ot the armature coininutators.

Lhe surfaces Means i'or machining an armature coniinutator mounted on a shaft supported in a hearing at one end, comprising a center'ng device for the hearing, a head and tail stocl engaging the opposite ends or" the shaft, means for supporting a tool in position machining the commutator of said armature and feeding the same along a line parallel with the axis of the armature as it is supported in said hearings, and an armature driving heit adiustalole into and out of contact with the surtace or" the armature and adapted to transmit rotary motion to sail armature While the tool is being fed along the cominntator si HARY G. lilllllill. 

